Salt water is a combination of salt and water, and is found in oceans, seas, and BRINE. It is composed of dissolved salts, mainly sodium chloride, and is denser than fresh water. OCEAN water is the largest source of salt water, covering over 70% of the Earth's surface. SEA water is also a major source of salt water, and is found in smaller bodies of water such as bays, gulfs, and estuaries. BRINE is a highly concentrated solution of salt water, and is used for a variety of purposes such as food preservation and industrial processes.